"The infection will kill him if we wait any longer."

"Can't he bleed it out, like Leatherhead did?!"

"Leatherhead is at least three times his size. Mikey would bleed to death before he got rid of it. Besides," Donnie says, shaking his head, "that was different."

Raph grits his teeth. He hates it when Donnie is right.

On the other side of the treehouse, Mikey whimpers in his sleep again. He's curled up on the dusty floor, shivering and sweating as his body tries to rid itself of the infection slowly spreading from the wound in his arm. It's only a few cuts from a broken window he had climbed through, eager to scour the store for supplies, but the infection had taken hold fast.

Leo straightens up, his expression steely.

"We're out of time," he says. "Donnie, can you do it?"

"Well, the procedure is simple enough, I just need—"

"But can you do it?" Donnie stares at his hands for a second, a rueful smile on his lips.

"You're asking if I can cut off my little brother's arm?" He looks over at Mikey and shakes his head. "I don't have any choice." There's a long moment of silence, and then Donnie gets to his feet.

"Get my toolbox," he says. "Find the others and bring them back up here. We'll need all the help we can get."

It only takes Leo a few minutes to gather the rest of their ragtag team and bring them back to the treehouse. They all look to Donnie for an explanation, but realization quickly dawns on their faces as he picks the saw out of his toolbox.

"Christ…" Karai mutters, and the color drains from Casey's face.

"Guys," says Donnie, snapping his fingers. "I need you to concentrate. Casey, get a fire going. I need it as hot as possible."

"Pine needles," Leatherhead says. "They will burn fast, but hot."

"Shitload of pine needles, got it," says Casey.

"Karai, give me your belt," Donnie says, as Casey runs out of the treehouse, chanting "Pine needles, pine needles, pine needles" to himself. "April, get the first aid kit. Raph…wake him up." Raph looks as pale as anyone's ever seen him, but he nods curtly and kneels beside Mikey.

"Wake up, buddy," he says gruffly, shaking his brother's shoulder. "We've got…we've got shit to do."

"I don't feel good," Mikey whines. He tries to tuck his head into his shell, but Raph grabs his chin. "I'm all hot and my arm hurts, Raph."

"I know. Don't go hiding in your shell, though, we need you out here," says Raph. "Donnie's gonna…" He opens and closes his mouth several times, but no sound comes out. Leo crouches down beside him.

"Mikey, Donnie is going to cut your arm off," he says gently. Mikey opens his eyes this time.

"What?"

"I have to remove your arm to keep the infection from spreading," says Donnie, looking everywhere but directly at his little brother.

"No—"

"I can take it off at the elbow, your balance won't be too compromised—"

"No way!"

"—lots of people survive and thrive with just one arm—"

"You're not chopping my arm off!" Mikey reaches out and grabs Raph's wrist, as if Raph can protect him from any of this. "Raph, tell him!"

"I…" Raph can't seem to find his voice, and he just shakes his head.

"Mikey, you'll die if I don't do this," Donnie says. "Do you hear me?"

"But—"

"You don't have a choice!"

"Lower your voice, Donatello," Leatherhead growls. "But he is right, Michelangelo—your life is in danger if the infected limb remains attached." Mikey stares at the floor, his eyes full of tears.

"I don't wanna," he whispers. The treehouse door bursts open before anyone can respond and Casey bounds in, his sweatshirt tied around a big bundle of pine needles and sticks.

"Let's do this," he says, and fishes a tattered book of matches out of his pants pocket. Everyone looks at Mikey again, but he doesn't say a word. Donnie takes Karai's belt and ties it around Mikey's upper arm, just above the crook of his elbow.

"Raph, Leo—hold him down."

Cutting through the flesh isn't so bad. Mikey screams and cries a lot, but it's not until Donnie starts sawing through the bone that it gets really hard. April and Karai throw their whole weight into helping Raph and Leo pin the youngest turtle down, trying to hold him as still as possible as Donnie cuts through the humerus.

"How's that fire, Casey?!" Leo yells over Mikey's keening.

"Hot and ready!" Casey shouts back. Donnie practically throws the saw at him.

"Heat this up until it's almost glowing," he says, and breaks Mikey's half-sawed bone in one swift move. Mikey shrieks anew, throwing his head back against the floor with a solid thunk.

"Leatherhead, get me a bottle of Raph's whiskey and get this—" Donnie shoves Mikey's now severed forearm away, leaving a streak of blood in its wake— "as far away from the treehouse as possible."

"I'll take it," Karai says quickly. "Leatherhead, take my spot." Leatherhead gives her a grateful look and they swap places.

"April, go with her," says Leo. "I don't want any of you going out alone."

"But—"

"We've got this under control," Leo assures her, and April reluctantly follows Karai out of the treehouse.

Donnie unscrews the cap of the bottle with his teeth since his hands are too slick with sweat and blood to grip it, and, eerily calm, he pours it over the wound. Mikey screams again, thrashing against his brothers and his best friend as pain overwhelms every other sense.

"What the fuck is that for?" Raph demands, as Casey brings the hot saw back over, and Donnie presses the flat side of the blade against Mikey's bloody stump by way of an answer. The smell of burning flesh makes them all gag, and, mercifully, Mikey passes out.